feat: fpw plugins, validation/crawl perf, WS stats, test DB isolation

- Add Free_Proxy_Website-style fpw_* plugins and register them
- Per-plugin crawl timeout (crawl_timeout_seconds=120); remove global crawl_timeout setting
- Validator: fix connect vs total timeout on save; SOCKS session LRU cache; drop redundant semaphore
- Validation handler uses single DB connection; batch upsert after crawl; WorkerPool put_nowait
- Remove unused max_retries from settings API/UI; settings maintenance SQL + init_db cleanup of deprecated keys
- WebSocket dashboard stats; ProxyList pool_filter and API alignment
- POST /api/proxies/delete-one for IPv6-safe deletes; task poll stops on 404
- pytest uses PROXYPOOL_DB_PATH=db/proxies.test.sqlite so tests do not wipe production DB
- .gitignore: explicit proxies.test.sqlite patterns; fix plugin_service ValidationException import

Made-with: Cursor

app/core/execution/worker_pool.py

@@ -65,9 +65,12 @@ class AsyncWorkerPool:
         logger.info(f"{self.name} stopped")
 
     async def submit(self, items: List[T]) -> None:
-        """提交一批任务到队列（阻塞直到有空位，天然背压）"""
+        """提交一批任务到队列（优先 put_nowait，队列满时再 await put）"""
         for item in items:
-            await self._queue.put(item)
+            try:
+                self._queue.put_nowait(item)
+            except asyncio.QueueFull:
+                await self._queue.put(item)
 
     async def drain(self) -> None:
         """等待队列中所有任务被消费完毕"""